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Title
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Novel lanthanide(III) porphyrin-based metal-organic frameworks : structure, gas adsorption, and magnetic properties
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Author
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Abstract
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| The present work focuses on the hydrothermal synthesis and properties of porous coordination polymers of metal-porphyrin framework (MPF) type, namely, {[Pr-4 (H2TPPS)(3)]center dot 11H(2)O}(n) (UPJS-10), {[Eu/Sm(H2TPPS)]center dot H3O+center dot 16H(2)O}(n) (UPJS-11), and {[Ce-4(H2TPPS)(3)]center dot 11H(2)O}(n) (UPJS-12) (H2TPPS = 4,4',4 '',4'''-(porphyrin-5,10,15,20-tetrayptetrakisbenzenesulfonate(4)). The compounds were characterized using several analytical techniques: infrared spectroscopy, thermogravimetric measurements, elemental analysis, gas adsorption measurements, and single-crystal structure analysis (SXRD). The results of SXRD revealed a three-dimensional open porous framework containing crossing cavities propagating along all crystallographic axes. Coordination of H2TPPS4- ligands with Ln(III) ions leads to the formation of 1D polymeric chains propagating along the c crystallographic axis. Argon sorption measurements at -186 degrees C show that the activated MPFs have apparent BET surface areas of 260 m(2)g(-1) (UPJS-10) and 230 m(2) g(-1) (UPJS-12). Carbon dioxide adsorption isotherms at 0 degrees C show adsorption capacities up to 1 bar of 9.8 wt % for UPJS-10 and 8.6 wt % for UPJS-12. At a temperature of 20 degrees C, the respective CO2 adsorption capacities decreased to 6.95 and 5.99 wt %, respectively. The magnetic properties of UPJS-10 are characterized by the presence of a close-lying nonmagnetic ground singlet and excited doublet states in the electronic spectrum of Pr(III) ions. A much larger energy difference was suggested between the two lowest Kramers doublets of Ce(III) ions in UPJS - 12. Finally, the analysis of X-band EPR spectra revealed the presence of radical spins, which were tentatively assigned to be originating from the porphyrin ligands. |
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Language
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English
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Source (journal)
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ACS Omega
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Publication
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American Chemical Society
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2021
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ISSN
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2470-1343
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DOI
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10.1021/ACSOMEGA.1C03327
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Volume/pages
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6
:38
(2021)
, p. 24637-24649
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ISI
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000703535900034
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Pubmed ID
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34604646
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Full text (Publisher's DOI)
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Full text (open access)
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